The present invention relates generally to valves, particularly microvalves, and more specifically relates to a valve that employs a very thin flexible sheet member to seal against at least one of two ports in a non-flexing, substantially flat backer member to provide or block fluid communication between passageways terminating at the ports at the valve site. The valve is particularly suited for use in valve matrixes or arrays of the general type used in flow networks for handling various types of fluids or liquids.
In accordance with an earlier invention covered by my U.S. Pat. No. 4,304,257, I disclosed a valve that includes a body member that has a firm and stable support surface and a flexible sheet member that has a surface for conforming and mating with the surface of the valve body member. There are at least two fluid flow channels in the surface of the body member separated from each other by a land portion. A mechanical actuator is employed to flex the sheet member between a first position in which a surface of the sheet is in mating and sealing engagement with the surface of the body member to block flow between the two channels and a second position in which the sheet surface is spaced from the first position to allow fluid flow across the land surface between the two flow channels.
The flexible sheet member is a manifold diaphragm sheet made of polyurethane or silicone and of sufficient thickness such that heads formed on the ends of stems of the mechanical actuators can be embedded in the sheet. This requires the sheet to have substantial thickness. Because the sheet is an elastomer, were it able somehow to be made thinner, it could be gas pervious which is undesirable.
The actuators are solenoid operated which are not only bulky but heavy and employ substantial power for actuation. This is somewhat limiting to the function of the valve, particularly when many similar valves are assembled together in a manifold environment. The actuators also require extremely sensitive adjustment.
In accordance with my earlier invention, the flexible sheet is pulled physically downwardly into an aperture so that the surface of the sheet which is engageable with the firm and stable support surface is withdrawn from that surface plating two or more fluid passageways in communication. The flexure is all in one direction, that is, downwardly from the horizontal and returned to the horizontal.
Also in accordance with my earlier invention, when the flexible sheet is pulled away from the support surface, it exposes the land which is coincident with the support surface. A space is created, which when filled with a fluid flowing from one channel or passageway, can then flow out the second or additional passageways in communication with the space. An improvement over my earlier patent allows flow across the land to be channeled or directed to permit such flow to take place substantially immediately upon the flexible sheet surface being withdrawn from the support surface rather than waiting for the space to become filled or substantially filled.
A further improvement to my earlier patent reduces the flexing of the flexible sheet to avoid undue stress concentration at any one point or points and secondly, to reduce the tendency of the sheet to become stressed beyond its yieldpoint.
The improvements to my earlier '257 patent are disclosed in my U.S. Pat. Nos. 4,848,722, 4,852,851 and 4,858,883 assigned to the same assignee as the present invention. In the above patents, a valve with a flexible sheet member and capable of solenoid actuation using fluid or vacuum is disclosed that has at least one track in contact with the mylar or flexible sheet wherein the surface is broken with a concave void or a "canal". In the valve described in the patents, the flexible sheet member is deformed or stretched at the valve site as it is flexed to engage and disengage against the curved surface of the valve site to provide the desired communication or block the flow of fluid between the passageways at the valve site. Although the wear is improved over my earlier patent with the above design, the flexible sheet member at the valve site still flexes approximately 50% from an at rest position and is still required to engage or seal against the ridges or edges of the channel ends or openings to provide the desired communication or block the flow of fluid between the passageways at the valve site.
A further disadvantage of the valve of the above patents is that the valve site cannot be made fail-safe in the event of a loss of pressure or vacuum to seal the flexible sheet against the valve site surface thus allowing fluid to communicate between passageways.
Accordingly it is a general aim of the present invention to provide a further improved valve with a flexible sheet member that substantially reduces the distance the sheet member must be flexed to provide the desired communication or block the flow of fluid between the passageways at the valve site.
It is a further aim in one embodiment of the present invention to provide an improved valve with a flexible sheet member that seals against at least one of two spaced holes or ports in a substantially flat, non-flexing surface and which holes or ports are in registration with respective passageways at the valve site to provide the desired communication or block the flow of fluid between the passageways at the valve site.
It is a still further aim of the present invention to provide an improved valve with flexible sheet member that is capable of actuation by means of a solenoid which seals the valve when at rest with a spring or mechanical hold down and a constant vacuum which opens the valve when the solenoid is excited.
It is yet a further aim to provide an improved valve with a flexible sheet member that is capable of actuation by means of pressure and vacuum through a three way valve which may be either built in or remote from the valve.
It is a yet further aim of the present invention to provide a valve array that is capable of a high density arrangement with mechanical solenoid operation to form a matrix of valve sites.
It is a still further aim of the present invention to provide an improved flow through valve with a flexible sheet member.